The invention relates to a distribution cabinet which is usually set up outdoors and accommodates the distribution installations for weak-current systems, for example telephone systems, with associated power-supply devices and cable-terminal/-connection devices for a certain area.
Nowadaysxe2x80x94in addition to having sufficient structural stability and resistance to vandalism, etc.xe2x80x94such distribution cabinets have to satisfy further requirements, for example excessive electromagnetic radiation must not be emitted to the surroundings, and, for use in warmer countries in particular, the temperatures in the interior of the distribution cabinet must not rise to too high a level, despite the heat-emitting electrical subassemblies accommodated there, nor must they drop to too low a level.
Such distribution cabinets are basically produced either from metal or from plastic, plastic combining the advantage of less expensive production with the advantage of an electrically non-conductive material, with the result that, even in the case of unplanned contact being established between the housing of the distribution cabinet and an electrical component, there is never a risk of a person who touches the housing from the outside receiving an electric shock.
As far as the sufficient cooling capability of such distribution cabinets is concerned, it is already known for cooling to be effected by air circulation. For this purposexe2x80x94up until now only in the case of distribution cabinets consisting of sheet steelxe2x80x94the body is of double-walled configuration, it being possible for the ambient air to circulate in the interspace between the walls, that is to say to pass in at the bottom and to pass out at the top, as a result of which, on the one hand, the interior is heated up by the sunlight and, on the other hand, heat is dissipated on the inner wall, which are heated up by the electrical subassemblies in the main chamber.
Such a double-walled construction is indeed theoretically possible even in the case of distribution cabinets produced from plastic. However, on account of the greater wall thicknesses which are necessary in this case, and of the outer and inner dimensions being predetermined by standards in the various countries, this would result in excessively small free spaces on the inside and overall dimensions on the outside.
In addition, it is extremely important for such distribution cabinets not to exceed the admissible maximum value of electromagnetic radiation emitted to the outside, that is to say for the EMC (electromagnetic compatibility) to be ensured.
a) Technical Object
The object of the present invention is thus to provide a distribution cabinet and an assembly kit for producing such a distribution cabinet, the distribution cabinet consisting at least partially of plastic and nevertheless providing sufficiently good shielding against electromagnetic radiation, on the one hand, and a sufficient cooling capability, on the other hand.
b) Solution of the Object
This object is achieved by the features of claim 1. Advantageous embodiments can be gathered from the subclaims.
Up until now, distribution cabinets produced from plastic usually comprised a base box, which was usually open on the top side and also on the underside, since the underground cables were introduced into the base unit, a body, which was positioned on the base and on which one or two doors or flaps for opening the body were provided, for the purpose of installing or maintaining and checking the electrical units in the interior of the body, and a cover protecting the body, open on the top side, and one upward against rain and other influences, and usually positioned in a sealed manner.
It was additionally possible for the body to have a base plate as an integral or separate component whichxe2x80x94apart from the through-passages for the cablesxe2x80x94separated off the main chamber in the interior of the body from the base chamber.
A distribution cabinet according to the invention may be produced from these known components by the addition of an installation frame which is made up, in particular, of deflected sections of an endless profile. The specific integration of the profile makes it possible, on the one hand, to simplify the assembly to form axe2x80x94three-dimensionalxe2x80x94installation frame to a very considerable extent and, in addition, to facilitate the optional fitting of EMC shielding and/or the production of a double-shell wall of the distribution cabinet for ventilation and cooling purposes.
The profile herexe2x80x94as seen in cross sectionxe2x80x94preferably has an approximately rectangular cross section, in particular two continuous outer surfaces running at right angles to one another. The other two, inwardly oriented outer surfaces each have an insertion pocket which is open on the outside and is intended for the insertion of insertion panels, of which the insertion direction is arranged parallel to the continuous outer surfaces and which are preferably also arranged as far as possible in the outward direction in the profile side surface thereof.
This preferably produces a cross-sectionally continuous hollow-chamber profile in the inner corner of the profile, this stabilizing the profile, in particular when the cross-sectional shape of the hollow chamber has one or more recesses, preferably directed outward.
In the case of essentially constant wall thicknesses being provided, these recesses are produced, on the one hand, by the already mentioned insertion pockets and, on the other hand, by at least one, preferably precisely one further pocket 57, which extends parallel to one of the insertion pockets and is open in the outward direction, but has undercuts, preferably arranged symmetrically in relation to one another in both flanks. These undercuts are used for arranging embracing a groove nut therein.
This configuration makes it possible, on the one hand, for three such profile sections to be connected to one another relatively easily to form a three-dimensional corner connection:
This takes place by two profile sections being cut to length and mitered and positioned one against the other. This three-dimensional corner connection is secured by an angle which is pushed, by way of its legs, into the open endsxe2x80x94from the miterxe2x80x94of the undercut of the pocket and is fixed there by means of, for example, clamping screws or else is fastened on the outsides of the two profile sections.
Since this angle or a groove nut has a threaded bore in the direction of the third, as yet missing, angle profile, this third angle can be positioned flush on the first two angles, which are already connected to one another, and fixed against the angle or the groove nut by means of a clamping screw, which is arranged in the longitudinal direction of the pocket, and within this pocket of the third profile, and can be screwed into the threaded bore of the angle or of the groove nut. This clamping screw is secured in its longitudinal direction in the third profile with the aid of a transversely running threaded bolt arranged in a transverse bore or with the aid of other means.
All of the additional elements necessary for the corner connection are located within the cross section of the three corner-forming profile sections.
It is possible for the profile configuration, furthermore, to be used very easily in order to complete the installation frame, formed from the profile sections, in that appropriately cut-to-size insertion panels are inserted into the insertion pockets, with the result that the respective side of the installation frame is a more or less closed side, that is to say when the panels are continuous panels which do not have any through-passages.
If the EMC shielding is to be achieved by means of the insertion panels, these panels will consist of metal or will have metallic components as a coating or addition, if the panels themselves consist of plastic. In addition, an EMC seal is then preferably positioned between the edges of the panels and the grooves of the insertion pockets accommodating them. Shielding made of a woven fabric or perforated metal sheets may also be utilized through placement outside the installation frame and/or inside the cabinet body.
These panels, however, may also serve for forming the inner shell of a double-shell distribution cabinet, the outer body forming the outer shell. The air space provided therebetween serves for ventilation and cooling purposes in thatxe2x80x94since the air space is open at the top and bottomxe2x80x94on account of the chimney effect air, preferably from the surroundings, flows in at the bottom and flows out at the top and is transported away in the interspace, in particular from the outer wall, which is irradiated by the sun. For reasons of cost and for heating-up reasons, the outer wall will preferably consist of plastic here.
It is thus possible, with the aid of a corresponding assembly kit, for the installation frame, which is located in the interior of the outer body, to be used not just for arranging the electrical components, but also for optional fitting with EMC shielding, with a second, inner shell for the purpose of a ventilated double-shell cabinet housing, it also being possible for both these things to be functionally combined by corresponding panels.
Irrespective of this, a further improvement may be provided by completion by means of further components, it being the case in particularxe2x80x94in contrast to the previously described, known componentsxe2x80x94that additional parts for supplementary purposes, rather than still having to consist of plastic, [lacuna] also [lacuna] of other materials, for example aluminum or sheet steel, in particular of high-grade steel, be this for reasons of shielding against electromagnetic radiation (EMC shielding) or for reasons of thermal conductivity.
Such an additional part may be formed by a top intermediate part, which is positioned between the top border of the body and the cover, which closes off the top, in particular in a sealed manner in relation to the body. This top intermediate part serves occasionally for heating purposes, but mostly for additional temperature reduction in the interior of the main chamber, that is to say in the interior of the body, and thus of the installation frame in the this interior is cooled by means of the top intermediate part, to be precise, depending on requirements, in different ways:
On the top intermediate part, which, in addition to a border running all the way round the outside, also has a false floor, which preferably seals the main chamber of the body in the upward direction, one or more bottom cooling structures may be fastened on the underside of the false floor, that is to say also, in certain circumstances, also projecting some way into the main chamber of the body. These cooling structures extract heat from the air circulating in the interior of the main chamber as it passes along beneath the ceiling, that is to say the underside of the false floor, in that said cooling structurexe2x80x94usually a ribbed structurexe2x80x94gives off its heat, by heat conduction, to the interior of the false floor, which is likewise a good heat conductor, the structure being fixed to the false floor or even possibly integrally formed therewith.
The top intermediate part itself, rather than being sealed, above its false floor, in the direction of the surroundings, has openings, for example slots which are arranged in the side borders and allow ambient air to pass in and out, said ambient air dissipating heat as it passes along the top side of the false floor. This can be enhanced if, in turn, a top cooling structure is arranged on the top side of the false floor, preferably at the same location as the bottom cooling structure. It is also possible for the top and bottom cooling structures to be formed integrally with one another and to be arranged in a sealed manner in a corresponding through-passage of the false floor.
This effect is more pronounced as the surface area of the cooling structure increases, for which reason said cooling structure will usually cover more than half, for example two thirds or three quarters of, the surface area of the false floor.
In order to optimize the passage of air along the cooling ribs on the top side of the false floor, it is advantageous, in particular, for these cooling ribs to be arrangedxe2x80x94as seen in the plan view of the top side of the top intermediate partxe2x80x94in particular radially in star form, for example extending away from the center of the false floor, and for the region around the geometrical crossover point of these radially running cooling ribs to be left free in order for a passive, that is to say non-driven, radial-flow impeller to be arranged there such that it can be rotated about a vertical axis. The radial-flow impeller in this case has blades which are curved arcuately in plan view in particular.
By virtue of such an arrangementxe2x80x94in particular if a sufficient number of ventilation slots of a sufficient size are provided all the way round the side borders of the top intermediate part, level with the cooling ribs and/or the fanxe2x80x94the impeller is driven by wind blown into the ventilation slots from the outside, and thus, on the opposite sides, forces air radially outward between the cooling ribs, as a result of which outside air constantly passes over a particularly large number of cooling ribs.
In addition, a functional opening is optionally arranged in the false floor, it being possible for said opening to be closed firmly by a functional cover, or for the functional cover thereof to be opened by hand or else automatically, namely when a certain threshold temperature in the interior of the main chamber is exceeded, or for said functional opening to serve instead, or in addition, for accommodating further components.
The functional parts which are inserted into the functional openingxe2x80x94it being immaterial here whether the functional parts extend more above or beneath the false floor in a vertical directionxe2x80x94may be an inserted air filter with an EMC filter, for passive cooling of the main chamber with the functional opening open, or else an active, electrically operated fan, which then extracts warm air by suction, through the functional opening, from the interior of the body, or else the above-described passive fan, which is then preferably placed vertically above the false floor, forces [lacuna] into the region above the false floor of the top intermediate part and, through the openings provided there, into the surroundings.
It is also possible to insert an air/air heat exchanger, which preferably has open primary and secondary circuits in each case, air from the main chamber, that is to say from the body, flowing through one circuit, while air from the region above the false floor, that is to say ambient air from the outside, flows through the other circuit. The air from the main chamber is thus always separated from the ambient air and sealed from the latter, with the result that the penetration of contaminants is prevented.
The flow of the two types of air through the respective open circuits of the heat exchanger may be assisted on one or on both sides in each case by driven, preferably electrically operated, fans. It is also possible for just one of the two circuits to be provided, while the other circuit is absent, and the other type of air just flows over a correspondingly large outer surface area of the heat exchanger and feeds and dissipates heat via conduction.
Another additional part may be formed by anxe2x80x94in particular specifically configuredxe2x80x94installation frame in the interior of the body. The installation frame is preferably a self-supporting frame which is made up of aluminum profiles, runs in the vicinity of the inside of the body, has a high level of stability, and on which the electrical subassemblies are fastened and connected to the cables.
For this purpose, the installation frame is preferably of cuboidal configuration with open side surfaces, the profiles running along all the edges of the cuboid. It is preferable here for the horizontally running transverse struts at the top, rear edgexe2x80x94as seen from the front doors of the bodyxe2x80x94to be offset downward, in order for it to be possible for necessary installations to be better fixed there.
In the front surface of the installation frame, a rectangular, vertically upright two-dimensional frame is additionally provided as a mounting rack, which is arranged on the top and bottom front transverse struts of the installation frame such that it can be displaced in the horizontal direction. The electrical subassemblies are fastened on said mounting rack and can thus be positioned in accordance with the position of the cables, running in from beneath, by virtue of the mounting rack being displaced. It is also possible for more than one such mounting rack to be provided in the installation frame.
Otherwise, all the outer surfaces of the installation frame are open, and are not closed over the surface area. In addition, the distribution cabinet has EMC shielding, which can be realized in different ways, but always has to consist of a material which does not allow electromagnetic radiation to pass through.
This material may be added, in a sufficient concentration, to the plastic of which the body and/or the doors and/or the cover and/or the base, etc. consist, or the abovementioned plastic parts may be provided on the inside with a coating which contains this material, or consists of this material, or the main chamber is lined with a woven fabric of this material, or with metal sheets or perforated metal sheets of this material, at least on its peripheral sides, preferably also at the bottom and top.
The fastening in the two last-mentioned cases may be provided either on the insides of the body or of the doors or on the outsides of the installation frame.
It is particularly advantageous here for the installation frame to be fastened not on the body but exclusively on the base, or on the bottom intermediate part positioned on the base, and, in addition, for no undercutsxe2x80x94as seen in the transverse directionxe2x80x94to be permitted between the installation frame and body.
This is intended to allow existing distribution cabinets to be converted without operation being interrupted in that the electrical components which are fixed and connected in the installation frame remain there and, in addition, need not be disconnected, but the cover and body can nevertheless be raised off in the upward direction.
This is often necessary in order to exchange the damaged body, or in order to exchange the body for another type of body, for example an EMC-proof body, or in order for it to be possible to install EMC shielding between the outside of the installation frame and the inside of the body and then to place the old body in position again.
A further additional part is formed by the bottom additional part, which is positioned between the base box, which is open at the top, and the bottom border of the body or of the installation frame.
This bottom intermediate part is likewise of tray-like design again, with a false floor and a peripheral border, and openings are likewise provided again in order to allow ambient air to penetrate into the region beneath the false floor.
The configuration selected here is preferably one in which, in the top region of the base box, the outer wall of the latter is set back inward, and a horizontal spacing, serving as an opening, thus remains between said wall of the base box and the outer border of the bottom intermediate part, with the result that said opening cannot be seen from the side or laterally at the top. The same principle can also be applied for the top intermediate part.
The false floor of the intermediate part, rather than being completely closed, has a plurality of cable through-passage openings distributed over its surface, it being possible for said openings optionally to be closed by covers which have a sealing action, on the one hand, against contamination, but also against electromagnetic radiation. For this reason, the bottom intermediate part and the covers closing the cable through-passage opening, in turn, is also produced from an EMC-shielding material, for example aluminum.
In addition, it is also possible for the false floor of said bottom intermediate part to have one or more functional openings, which may analogously serve the same purposes, and thus for the installation of the same functional parts, as have been described with reference to the top intermediate part.
For this reason, it is possible for the false floor to be located either in the top height region of the vertical extent of said bottom intermediate part, if said functional parts are positioned beneath the false floor, or the other way roundxe2x80x94and this is the preferred embodimentxe2x80x94in the bottom region of the vertical extent, in order to provide space, above the false floor, for arranging such functional parts as a fan, which, for power-supply purposes, has to be connected to the electrical subassemblies of the main chamber and, in addition, requires space.
By virtue of adding one or more of the above-mentioned additional parts or additional measures to the already known components, it is possible to produce, depending on the use purpose, the specific distribution cabinet from this assembly kit.
c) Exemplary Embodiments